When an electronic component is mounted on a substrate, a flip-chip mounting is conducted by using bumps. At this time, bumps have a function of obtaining an electrical connection between the electronic component and the circuit board, and mechanically fixing the electronic component to the circuit board. In addition, the underfill is provided between bumps, and the junction of the electronic component with the circuit board is reinforced. Reinforcement is disclosed in, for example, Japanese Laid-Open Patent Publication Nos. 2007-88293 and 2007-12695.
However, when the underfill is used, there is a case where it becomes difficult to remove components. If it is impossible to remove components, the use of the whole of a circuit board to which an expensive component is mounted becomes impossible.